package thread.gc;

import java.util.Hashtable;

/**
 * @author ykh
 */
public class t3 {
    public static void main(String[] args) {
        Hashtable table = new Hashtable();
        // 线程1，线程2
        if (table.get("key") == null) {
            table.put("key", "value");
        }
    }
}
